Method and device for transdermal delivery of parathyroid hormone using a microprojection array

ABSTRACT

A method and a drug delivery system for transdermally administering parathyroid hormone (PTH) in a pulsatile fashion are provided, where the drug delivery system comprises an array of microprojections each comprising PTH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.16/786,906, filed Feb. 10, 2020, now allowed, which is a Divisional ofU.S. application Ser. No. 15/623,305, filed Jun. 14, 2017, which is acontinuation of U.S. application Ser. No. 13/101,071, filed May 4, 2011,now U.S. Pat. No. 9,687,641, issued Jun. 27, 2017, which claims thebenefit of U.S. Provisional Application No. 61/331,226, filed May 4,2010, each of which is incorporated by reference herein.

REFERENCE TO SEQUENCE LISTING, TABLE OR COMPUTER PROGRAM

A Sequence Listing is being submitted electronically via USPTO PatentCenter in the form of an XML file, created Jul. 14, 2022, and named“091500-0970_Sequence_Listing.XML” (2 kilobytes), the contents of whichare incorporated herein by reference in their entirety.

TECHNICAL FIELD

This disclosure relates generally to a method and drug delivery systemfor transdermally administering parathyroid hormone (PTH) using an arrayof microprojections, and related features thereof.

BACKGROUND

Human parathyroid hormone (hPTH) is an 84 amino acid protein that issecreted by the parathyroid gland; PTH is involved in calcium andphosphorus homeostasis and the control of bone growth and density. Twoforms of recombinant hPTH have been evaluated in clinical trials, hPTH(1-34) and the full length 84-amino acid, hPTH (1-84). hPTH (1-34) is anN-terminal fragment of PTH, which, along with fragment 1-38, retains thefull biological activity of the intact protein.

A recombinant, rDNA-derived, injectable form of hPTH (1-34)(teriparatide) was approved in the United States in 2002 for thetreatment of severe osteoporosis and is sold under the tradename FORTEO®(Eli Lilly), referred to hereafter as subcutaneously injectedteriparatide. The subcutaneously injected teriparatide is typicallyprescribed for women with a history of osteoporotic fracture, thosehaving multiple risk factors for fracture, or who have failed or areintolerant of other osteoporosis therapies. In postmenopausal women,subcutaneously injected teriparatide has been found to increase bonemineral density and reduce the risk of vertebral and non-vertebralfractures. Subcutaneously injected teriparatide has also been describedto increase bone mass in men with primary or hypogonadal osteoporosiswho are at a high risk for fracture. In men with primary or hypogonadalosteoporosis, subcutaneously injected teriparatide has similarly beenreported to increase bone mineral density. In 2009, subcutaneouslyinjected teriparatide was also approved for treatment of osteoporosis inmen and women associated with sustained systemic glucocorticoid therapyat high risk for fracture.

Bone degenerative diseases such as osteoporosis occur in a substantialportion of the senior adult population. Osteoporosis encompasses aheterogeneous group of disorders that represent a major risk for bonefractures, and a substantial burden on the health care system. Billionsof dollars are spent annually on medical care for the treatment ofosteoporosis. Clinically, osteoporosis is characterized by diminishedbone mass, decreased bone mineral density (BMD) and bone mineral content(BMC), and loss of bone architecture resulting in decreased bonestrength and increased risk of bone fracture.

While a number of antiresorptive agents including calcitonin,bisphosphonates, estrogen, and selective estrogen receptor modulators(SERMs) prevent further bone loss, they do not rebuild bone once it hasbeen lost. This is in contrast to subcutaneously injected teriparatide,which represents the first-FDA approved anabolic bone building agent forthe treatment of osteoporosis. PTH or PTH (1-34) is thought to exert itseffects through receptor-mediated activation of two intracellularsignaling pathways via (1) adenylate cyclase and protein kinase A, and(2) phospholipase C and protein kinase C. PTH (1-34) builds bone mass,restores bone architecture, and reduces the risk of vertebral andnon-vertebral bone fractures in osteoporotic patients who are at highrisk of fracture (R. Neer, NEJM, 344:1434, 2001).

As a peptide product, PTH (1-34) requires daily subcutaneousinjections—an administration regime that is less than ideal. Indeed,most patients have an aversion to self-injection of drugs, and the needto visit a clinic or doctor's office for administration is inconvenientand burdensome. Moreover, severely osteoporotic patients may be unableto self-administer such injections, such that each of the foregoingfactors can contribute to poor patient compliance.

While other forms of administration have been suggested, such as oraldelivery to the stomach, transdermal delivery, and nasopharyngealabsorption, none of these delivery routes has been proven to beparticularly effective and each suffers from certain drawbacks. Oraldelivery results in very low bioavailability of polypeptide drugs,usually below 1%, due to degradation in the gastrointestinal tract.Moreover, the epithelial lining of the gastrointestinal tract isimpermeable to most polypeptides. Nasopharyngeal and passive transdermaldelivery avoid the problems of enzyme degradation, but usually requirepenetration enhancers in order to effect systemic absorption. Even withsuch penetration enhancers, bioavailability will usually be very low,and the penetration enhancers can often cause undesirable irritation. Inthe case of nasopharyngeal administration, penetration enhancers canoften damage the nasal epithelium and chronic use has been associatedwith hyperplasia of the nasal lining.

It is presently believed that PTH is most effectively delivered to apatient in a pulsatile fashion to achieve active bone formation. That isto say, plasma concentrations of PTH should ideally rise rapidly afteradministration (rapid onset) and fall rapidly after a peak has beenreached (rapid decline), generally resulting in a spike in the plasmaconcentration profile. Thus, a particularly desirable method ofadministration of PTH is one that achieves such a plasma concentrationprofile.

For at least these reasons, it would be desirable to provide analternative delivery method for parathyroid hormone which is patientacceptable. Any such method should avoid subcutaneous injection, limitirritation to the skin and body mucosa, and provide a desired pulsatiledelivery profile as described above, among having other advantageousfeatures. Such method should ideally provide for high levels of PTHbioavailability, be amenable to self-administration by the patient, beminimally invasive, and ideally provide a pharmacokinetic profile thatis similar to, or preferably improved over, that achieved uponsubcutaneous administration.

BRIEF SUMMARY

The present disclosure is directed generally to a device and method oftransdermally administering PTH, inclusive of PTH analogs, fragments,salts, etc., in a pulsatile fashion to a mammalian subject, where themethod results in pharmacokinetics and a related delivery profile thatare surprisingly superior to subcutaneously administered PTH,particularly with respect to the rapid pharmacokinetics achieved.Additional advantageous features achieved by the device and methods ofthe invention are described in greater detail herein.

In a first aspect, provided herein is a method of transdermallyadministering PTH in a pulsatile fashion to a mammalian subject. Themethod comprises applying to a skin site of a subject a microprotrusionarray comprising a plurality of microprotrusions extending from anapproximately planar base, each microprotrusion comprising an endportion distal to the base and an upper portion proximal to the base, atleast the end portion comprising parathyroid hormone (PTH) in awater-soluble polymer matrix; inserting all or a portion of theplurality of microprotrusions into the skin, and maintaining the arrayon the skin site for 15 minutes or less, whereby at least a portion ofthe end portions of the plurality of microprotrusions detach from themicroprotrusion array; and whereby the method achieves an average timeto maximum PTH plasma concentration (T_(max)) of about ten minutes orless.

In one embodiment, the PTH is human parathyroid hormone (1-34).

In yet another embodiment, the microprotrusion array comprises fromabout 1500 to about 3200 microprotrusions, more preferably from about2200 to about 3200 microprotrusions.

In yet a further embodiment, the microprotrusion array possesses adiameter ranging from about 8 millimeters to about 14 millimeters.

In yet an additional embodiment related to any one or more of theforegoing, the water-soluble matrix comprises dextran and sorbitol,along with additional optional excipients. For example, in a furtherembodiment, the water-soluble matrix further comprises histidine andhistidine hydrochloride.

In a further embodiment, the microprotrusions themselves comprise PTH ina water-soluble polymer matrix, rather than having PTH present as acoating on the microprotrusions. That is, the PTH is admixed with and/orincorporated into the water-soluble polymer matrix from which at leastthe tip portions of each microprojection is formed.

In yet another embodiment of the method, the water-insoluble polymercomprises poly(lactic acid-co-glycolic acid).

In a further embodiment of the method, the base and the upper portion ofthe microprotrusion array comprise the same water-insoluble polymer.

In yet another embodiment related to the foregoing, the base and theupper portion of the microprotrusion array comprise the same material.

In a further embodiment, the end portion and the upper portion of eachmicroprotrusion in the microprotrusion array are composed of awater-insoluble polymer material that dissolves or biodegrades afterinsertion into the skin.

In another embodiment, the microprotrusion array comprises a dose ofPTH, and at least about 80% of the dose is disposed in the end portionsof the microprotrusions in the array.

In another embodiment of the method, the array is maintained on the skinsite for no more than about 10 minutes, alternatively for about 10minutes or less, alternatively for a time between 1 second and 10minutes, inclusive, or between 5 seconds, 10 seconds, 15 seconds and 10minutes.

In yet another embodiment, the array is maintained on the skin site forno more than about 5 minutes, alternatively for about 5 minutes or less.

In yet an additional embodiment, the method is effective to deliver atleast about 55 percent of the total dose of PTH in the array to thesubject. In another embodiment, the method is effective to deliver atleast about 60 percent of the total dose of PTH in the array to thesubject, more preferably at least about 65 percent of the total PTH dosein the array, based on a residual analysis of the device.

In yet another embodiment, the microprotrusion array is applied to theabdomen of the subject.

In yet a further embodiment, the method achieves an eliminationhalf-life (t_(1/2)) of PTH that is at least about 15%, 20%, 22% 25% or30% lower than the elimination half-life (t_(1/2)) of the same dose ofPTH administered subcutaneously.

In a second aspect, provided herein is a microprojection array for usein delivering hPTH in accord with the delivery parameters as describedin any one or more of the foregoing embodiments.

In yet a third aspect, a kit comprising (i) a microprotrusion arraycomprised of a plurality of microprotrusions extending from anapproximately planar base, each microprotrusion comprising an endportion distal to the base and an upper portion proximal to the base,the end portion of each microprotrusion comprising PTH in awater-soluble polymer matrix, said array comprising a therapeuticallyeffective amount of PTH, and (ii) an applicator-assembly to which themicroprotrusion array is insertable or affixable or, in anotherembodiment, (ii) an applicator to which the microprotrusion array isinsertable or affixable, is provided.

In one embodiment, the microprotrusion array is provided in the kitsecured to a support or holding member, such as a plunger, that isinsertable into the applicator assembly.

In another embodiment of the third aspect, the kit further comprises anapplicator assembly comprising a housing in which the array supportmember and microprotrusion array can be disposed, and an energy-storagemember that, in one embodiment, is movable between first and secondstable configurations.

In one or more related embodiments, the kit comprises a microprotrusionarray according to one or more of the array embodiments describedherein.

In yet another embodiment, the applicator assembly further comprisesfasteners to temporarily connect the housing and the energy storagemember prior to assembly.

In a more specific embodiment of the kit, the applicator assembly ispackaged in a first package or protective container.

In yet another embodiment of the kit, the microprotrusion array and anarray support member are packaged together in a second package orprotective container.

In a further embodiment, the kit comprises (i) a packaged applicatorassembly and (ii) a packaged microprotrusion array and array supportmember that is insertable into the applicator assembly prior to use.

Additional embodiments of the present method, microprojection array,kit, and the like will be apparent from the following description,drawings, examples, and claims. As can be appreciated from the foregoingand following description, each and every feature described herein, andeach and every combination of two or more of such features, is includedwithin the scope of the present disclosure provided that the featuresincluded in such a combination are not mutually inconsistent. Inaddition, any feature or combination of features may be specificallyexcluded from any embodiment of the present invention. Additionalaspects and advantages of the present invention are set forth in thefollowing description and claims, particularly when considered inconjunction with the accompanying examples and drawings.

These and other objects and features of the invention will become morefully apparent when read in conjunction with the following detaileddescription.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 demonstrates a fully assembled applicator.

FIG. 2 is demonstrates an exploded view of the applicator of FIG. 1 .

FIG. 3 is a plot of hPTH (1-34) plasma concentration (pg/mL) versus timefor an illustrative microprotrusion array-based hPTH transdermaldelivery system in comparison to subcutaneous administration of hPTH(1-34) as described in detail in Example 11. Values of maximum plasmaconcentration and Tmax for the treatments shown are as follows:(transdermal delivery of hPTH via a microprotrusion array known underthe tradename MicroCor®, 32 μg: Cmax: 180 μg/mL, Tmax: 8.1 mins;MicroCor® 64 μg: Cmax: 336 μg/mL, Tmax: 7.4 mins; subcutaneouslyinjected teriparatide (Forteo®) 20 μg: Cmax: 85 μg/mL, Tmax: 0.44 mins).

FIG. 4 demonstrates dose-normalized AUC (area under the curve) values(μg*min/mL*μg) for an illustrative microprotrusion array-based hPTHtransdermal delivery system in comparison to subcutaneous administrationof hPTH as described in detail in Example 11.

FIG. 5 is a graph illustrating mean Cmax (pg/mL) values for each of thethree treatment regimes examined: an illustrative microprotrusionarray-based hPTH transdermal delivery system (MicroCor® 32 μg dose andMicroCor® 64 μg dose) in comparison to subcutaneous administration(Forteo®, 20 μg dose) as described in detail in Example 11.

FIG. 6 is a graph illustrating mean Tmax (minutes) values for each ofthe three treatment regimes examined: an illustrative microprotrusionarray-based hPTH transdermal delivery system (MicroCor® 32 μg dose andMicroCor® 64 μg dose) in comparison to subcutaneous administration(Forteo®, 20 μg dose) as described in detail in Example 11.

FIG. 7 is a graph illustrating mean T½ (minutes) values for each of thethree treatment regimes examined: an illustrative microprotrusionarray-based hPTH transdermal delivery system (MicroCor® 32 μg dose andMicroCor® 64 μg dose) in comparison to subcutaneous administration(Forteo®, 20 μg dose) as described in detail in Example 11.

FIG. 8 is a graph illustrating normalized plasma concentration valuesversus time (hours) for each of the three treatment regimes examined: anillustrative microprotrusion array-based hPTH transdermal deliverysystem (MicroCor® 32 μg dose—open squares and MicroCor® 64 μgdose—closed squares) in comparison to subcutaneous administration(Forteo®, 20 μg dose, closed circles) as described in detail in Example11.

FIGS. 9A-9B depict schematically in cross-section exemplarymicroprojection arrays.

DETAILED DESCRIPTION

Various aspects now will be described more fully hereinafter. Suchaspects may, however, be embodied in many different forms and should notbe construed as limited to the embodiments set forth herein; rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey its scope to those skilled in theart.

The practice of the present disclosure will employ, unless otherwiseindicated, conventional methods of chemistry, biochemistry, andpharmacology, within the skill of the art. Such techniques are explainedfully in the literature. See, e.g.; A. L. Lehninger, Biochemistry (WorthPublishers, Inc., current addition); Morrison and Boyd, OrganicChemistry (Allyn and Bacon, Inc., current addition); J. March, AdvancedOrganic Chemistry (McGraw Hill, current addition); Remington: TheScience and Practice of Pharmacy, A. Gennaro, Ed., 20th Ed.; Goodman &Gilman The Pharmacological Basis of Therapeutics, J. Griffith Hardman,L. L. Limbird, A. Gilman, 10th Ed.

Where a range of values is provided, it is intended that eachintervening value between the upper and lower limit of that range andany other stated or intervening value in that stated range isencompassed within the disclosure. For example, if a range of 1 μm to 8μm is stated, it is intended that 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, and 7 μmare also explicitly disclosed, as well as the range of values greaterthan or equal to 1 μm and the range of values less than or equal to 8μm.

Definitions

It must be noted that, as used in this specification, the singular forms“a,” “an,” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to a “polymer” includesa single polymer as well as two or more of the same or differentpolymers, reference to an “excipient” includes a single excipient aswell as two or more of the same or different excipients, and the like.

In describing and claiming the present invention, the followingterminology will be used in accordance with the definitions describedbelow.

“Pulsatile delivery” or delivery in a pulsatile fashion refers to arapid rise in blood plasma concentration of drug such as PTH afteradministration, followed by a rapid decline of blood plasmaconcentration of drug following attainment of Cmax (i.e., generallycharacterized by a “spike” in the concentration profile).

“Transdermal” refers to the delivery of an agent such as PTH into and/orthrough the skin for local or systemic therapy.

Reference to a “PTH”, or a PTH-agent or to “hPTH (1-34)”, as usedherein, is meant to include, without limitation, hPTH (1-34), hPTHsalts, teriparatide, and the like, including recombinant hPTH (1-34),synthetic hPTH (1-34), and simple known derivatives of hPTH (1-34), suchas hPTH (1-34) amide. Examples of hPTH salts include, withoutlimitation, salts having counter-ions such as acetate, propionate,butyrate, pentanoate, hexanoate, heptanoate, levulinate, chloride,bromide, citrate, succinate, maleate, glycolate, gluconate, glucuronate,3-hydroxyisobutyrate, tricarballylicate, malonate, adipate, citraconate,glutarate, itaconate, mesaconate, citramalate, dimethylolpropinate,tiglicate, glycerate, methacrylate, isocrotonate, beta-hydroxibutyrate,crotonate, angelate, hydracrylate, ascorbate, aspartate, glutamate,2-hydroxyisobutyrate, lactate, malate, pyruvate, fumarate, tartarate,nitrate, phosphate, benzene, sulfonate, methane sulfonate, sulfate andsulfonate. A PTH-agent as described herein is meant to include any andall forms thereof, including free base and acid forms, charged oruncharged forms, stereoisomers, chiral forms, and the like.

The terms “microprotrusion”, “microprojection” or “microneedle” are usedherein to refer to elements adapted to penetrate or pierce the stratumcorneum or other biological membranes. For example, illustrativemicroprotrusions or microprojections may include, in addition to thoseprovided herein, microblades as described in U.S. Pat. No. 6,219,574 andCanadian Patent Application No. 2,226,718, edged microneedles asdescribed in U.S. Pat. No. 6,652,478, and microprotrusions as describedin US Patent Publication No. US 2008/0269685.

“Substantially” or “essentially” means nearly totally or completely, forinstance, 95% or greater of some given quantity.

“Optional” or “optionally” means that the subsequently describedcircumstance may or may not occur, so that the description includesinstances where the circumstance occurs and instances where it does not.

A material that is “water-soluble” such as the polymer matrix describedherein, is dissolvable at physiological pH, such that the materialdissolves into or within the skin.

Overview

As described above, provided herein is a method and drug delivery systemfor transdermally administering parathyroid hormone (PTH) using an arrayof microprojections. The method and related drug delivery systemprovides several unexpected advantages over subcutaneous administration,in particular with the pharmacokinetic profile achieved, especially itsrapid on-set to Cmax and subsequent rapid elimination rate, thuspermitting a pulsed delivery profile. The method, exemplarymicroprojection arrays, and related features will now be described ingreater detail below.

MicroProjection Array

General features of a microprojection array for use in the instantmethod are described in detail in U.S. Patent Publication No. US2008/0269685, the entire content of which is explicitly incorporatedherein by reference, and described more fully below. See, in particular,FIGS. 3, 4, 5A, 5B, 5C and 6 .

In reference to the microprojections themselves, in general, themicroprojections have a height of at least about 100 μm, or at leastabout 150 μm, or at least about 200 μm, or at least about 250 μm, or atleast about 300 μm. In general, the microprojections have a height of nomore than about 1 mm, no more than about 500 μm, no more than about 300μm, or in some cases no more than about 200 μm or 150 μm. Themicroprojections may have an aspect ratio (height to diameter at base)of at least 10:1, preferably at least about 5:1, more preferably atleast about 3:1, or at least about 2:1, or at least about 1:1. Anillustrative shape for the microprojections is a cone with a polygonalbottom, for example, being hexagonal or rhombus-shaped. Additionalmicroprojection shapes include those provided, for example, in U.S.Patent Publication No. 2004/0087992. While the array itself may possessany of a number of shapes, the array is generally sized to possess adiameter of from about 5 millimeters to about 25 millimeters, or fromabout 7 to about 20 millimeters, or from about 8 to about 14millimeters. Exemplary diameters include 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25 millimeters.

The microprojections may in some cases have a shape which becomesthicker towards the base, for example microprojections which haveroughly the appearance of a funnel, or more generally where the diameterof the microprojection grows in a faster than linear fashion withrespect to distance to the microprojection's distal end. Such a shapemay, for example, facilitate drug loading. Where microprojections arethicker towards the base, a portion of the microprojection adjacent tothe base, which may be referred to herein as a “backing portion” or‘foundation’ or as an “upper portion” may be designed not to penetratethe skin.

Generally, the number of microprotrusions in the array is preferably atleast about 100, at least about 500, at least about 1000, at least about1400, at least about 1600, or at least about 2000. For example, thenumber of microprotrusions in the array may range from about 1000 toabout 4000, or from about 2000 to about 4000, or from about 2000 toabout 3500, or from about 2200 to about 3200. The area density ofmicroprotrusions, given their small size, may not be particularly high,but for example the number of microprotrusions per cm² may be at leastabout 50, at least about 250, at least about 500, at least about 750, atleast about 1000, or at least about 1500. An illustrativemicroprotrusion array is described herein in Examples 9-11.

Examples of forming various microprotrusion arrays having differentconfigurations are provided in Examples 1-7. Generally, an array isprepared by (a) providing a mold with cavities corresponding to thenegative of the microprotrusions, (b) filling the mold with a castingsolution comprising a biocompatible material such as a biocompatiblepolymer and a solvent, (c) removing the solvent, and (d) demolding theresulting array from the mold. The solution preferably contains anactive ingredient such as PTH. In one or more embodiments, themicroprojections themselves comprise PTH in a water-soluble polymermatrix, as opposed to having the PTH present as a coating on amicroprojection or microneedle made of a different, biocompatiblematerial such as a metal.

The molds can be made using a variety of methods and materials.Materials for forming a mold include ceramic materials, siliconerubbers, polyurethanes, and waxes. An exemplary silicone rubber systemis the Sylgard® system from Dow Corning (Midland, Mich.), for exampleSylgard® 184. Nusil MED 6215, 6210 is an alternative system availablefrom NuSil Technology (Carpinteria, Calif.).

The molds can be prepared by any of a number of methods includingcasting the liquid mold material over a master microneedle array andallowing the material to dry and solidify by curing the liquid moldmaterial over a master microneedle array so it solidifies, such curingbeing affected by temperature or other means, by heating the moldmaterial until it melts, followed by casting the melted liquid overmicroarray, and allowing the material to cool and solidify, or bypressing the master microneedle array into the mold material. The moldscan also be made by plating metal (such as nickel, copper or gold) ontoa master microneedle array.

The solution which is cast preferably comprises one or more polymers ina solvent and an active ingredient (i.e., PTH). The polymers should bebiocompatible, in some cases, biodegradable. By this term is meant thata polymer will degrade under expected conditions of in vivo use (e.g.,insertion into skin), irrespective of the mechanism of biodegradation.Exemplary mechanisms of biodegradation include disintegration,dispersion, dissolution, erosion, hydrolysis, and enzymatic degradation.One preferred mechanism of biodegradation is dissolution, where thepolymer is water-soluble.

Biocompatible, biodegradable, or bioerodible polymers for use in theinstant microprojection arrays include poly(lactic acid) (PLA),poly(glycolic acid) (PGA), poly(lactic acid-co-glycolic acid)s (PLGAs),polyanhydrides, polyorthoesters, polyetheresters, polycaprolactones(PCL), polyesteramides, poly(butyric acid), poly(valeric acid),polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol(PEG), block copolymers of PEG-PLA, PEG-PLA-PEG, PLA-PEG-PLA, PEG-PLGA,PEG-PLGA-PEG, PLGA-PEG-PLGA, PEG-PCL, PEG-PCL-PEG, PCL-PEG-PCL,copolymers of ethylene glycol-propylene glycol-ethylene glycol(PEG-PPG-PEG, trade name of Pluronic® or Poloxamer®), dextran,hetastarch, tetrastarch, pentastarch, hydroxyethyl starches, cellulose,hydroxypropyl cellulose (HPC), sodium carboxymethyl cellulose (Na CMC),thermosensitive HPMC (hydroxypropyl methyl cellulose), polyphosphazene,hydroxyethyl cellulose (HEC), other polysaccharides, polyalcohols,gelatin, alginate, chitosan, hyaluronic acid and its derivatives,collagen and its derivatives, polyurethanes, and copolymers and blendsof these polymers. A preferred hydroxyethyl starch has a degree ofsubstitution of in the range of 0-0.9.

The biodegradability or dissolvability of the microprojection array maybe facilitated by the inclusion of sugars. Exemplary sugars includedextrose, fructose, galactose, maltose, maltulose, iso-maltulose,mannose, lactose, lactulose, sucrose, and trehalose. Sugar alcohols, forexample lactitol, maltitol, sorbitol, and mannitol, may also beemployed. Cyclodextrins can also be used advantageously in microneedlearrays, for example α, β, and γ cyclodextrins, for examplehydroxypropyl-β-cyclodextrin and methyl-β-cyclodextrin. Sugars and sugaralcohols may also be helpful in stabilization of peptides and proteinsand in modifying the mechanical properties of the microprojections byexhibiting a plasticizing-like effect.

An exemplary polymer effective for forming a casting solution to fill inthe tips or end portion of the microprojections is the polysaccharide,dextran (e.g., Dextran 1, Dextran 10, Dextran 20, Dextran 40, Dextran70, Dextran 75, and mixtures thereof), optionally combined with thesugar alcohol, sorbitol.

A particularly preferred formulation for filling the end portion or tipof the microprojections comprises hPTH (1-34), dextran, and sorbitol. Ina preferred embodiment, the PTH is provided in a water-soluble matrix.The water-soluble matrix comprises dexran, sorbitol, and PTHcounter-ion, if contained in the PTH source material. Additionalcomponents may include buffers such as histidine and histidinehydrochloride.

The polymers used may possess a variety and range of molecular weights.The polymers may, for example, have molecular weights of at least about1 KD, at least about 5 kD, at least about 10 kD, at least about 20 kD,at least about 22 kD, at least about 30 kD, at least about 50 kD, or atleast about 100 kD.

Exemplary solvents for casting include water, alcohols (for example, C₂to C₈ alcohols such as propanol and butanol), and alcohol esters, ormixtures of these. Such solvents are typically useful for castingcomponents which themselves are water-soluble. Other solvents includeesters, ethers, ketones, nitriles, lactones, amides, hydrocarbons andtheir derivatives as well as mixtures thereof.

The mold itself, or portions of it, may be treated to improve wettingusing any of a number of well-known surface treatments, such assurfactant coating, salt coating, radiofrequency treatment, plasmatreatment and the like.

During solvent removal, the volume of the cast solution will naturallydiminish. With an appropriate choice of solvents, it is possible for thedistal ends of the microprojections—those furthest from the base—tobecome finer as a result of solvent removal. Illustrative tip diametersinclude those of less than about 10 μm, or less than about 5 μm, lessthan 2 μm, less than about 1.5 μm, or even less than about 1 μm.

The microprotrusion array may be prepared to contain, in addition toPTH, any of a number of different polymers and other additives.Generally, the array comprises an approximately planar base and aplurality of microprotrusions attached thereto. The array typicallyfurther contains a plurality (meaning 2 or more) of layers arrangedroughly parallel to the plane of the base, where at least two of theplurality of layers comprise different polymers. One layer of theplurality of layers comprises PTH. Optionally, at least one layer of thearray or the array housing adheres to human skin.

Various embodiments include the following. For example, compared to theoverall volume of the microprojection array, the microprojectionsthemselves may possess a higher amount of PTH. In certain instances, theend portion of the microprojection comprises a higher amount of PTH thanthe upper portion and/or the base. When the PTH is cast in awater-soluble, dissolvable matrix, the tips or end portions of themicroprojections will dissolve more rapidly than other portions of thearray, making delivery of drug particularly efficient. Furthermore, incertain treatment protocols, the array may be left on the skin for onlya short period of time during which essentially only themicroprojections can dissolve to a substantial extent. The desirabilityof placing a higher amount of active such as PTH in the projectionsthemselves is particularly high when the active is costly. An arrayconfiguration that is effective to achieve a high amount of active inthe tips or end portions of the microprojections themselves is to loador place a first drug-containing polymer layer in the tips or endportion of the microprojections (or in a substantial portion of themicroprojections), and a second polymer layer which includes the upperportion of base or a substantial proportion of the base, but is absentdrug (PTH).

FIGS. 9A-9B depict schematically in cross-section two exemplarymicroprojection arrays suitable for use in the methods described herein.In the first microprojection array shown in FIG. 9A, microprojectionarray 50 comprises a base 58 and a plurality of microprojections, suchas representative microprojection 56. The microprojection arraycomprises two layers, a first layer 52 and a second layer 54 (shaded).The microprojections, taken in this embodiment to be the portions of thearray that extend from the planar surface defined by the proximal skincontacting side of first layer 52, are composed of the material fromwhich first layer 52 is manufactured. In this embodiment, second layer54 and first layer 52 collectively define the base of themicroprojection array, the base having a planar surface from which themicroprojections extend. The microprojections extending from layer 52are comprised of the material from which layer 52 is fabricated. Thatis, the microprojections are fabricated from a first material and all ora portion of the base is fabricated from the same material. In anotherembodiment, the microprojections are fabricated from a first materialand a portion of the base is fabricated from a different material.

In another embodiment of a microprojection array 60 depicted in FIG. 9B,there are also a plurality of microprojections, such as microprojection66 which is representative. Each microprojection in the array has an endportion or distal tip 62 that contacts and penetrates (upon applicationof force) the stratum corneum, and an upper portion proximal to a planarbase 64. In this embodiment, the base member and the upper portion ofeach microprotrusion is comprised of a first material, indicated by theshading in the drawing. The end portion of each microprotrusion isfabricated from a different material. In one embodiment, the materialfrom which the base and upper portions are fabricated is awater-insoluble polymer, and the end portion of each microprotrusion isfabricated from a second or different material that is a water-solubleor dissolvable material. The PTH can be incorporated into only the endportion of each microprotrusion (i.e., “drug-in-tip” as described insome examples) or can be incorporated into the end portion and the upperportion of each microprotrusion. Of course, PTH can also be incorporatedinto the base, but is normally not for cost of goods and/or safetyreasons. In another embodiment, the first material forming the base andupper portion of each microprotrusion, and the material forming the endportion of each microprotrusion are the same polymer material,preferably a dissolvable or biodegradable water soluble polymer, anddiffer only in that the material forming the end portions contains anactive agent such as PTH and the material forming the base and upperportions contain no active agent or a different active agent than theend portions. In one embodiment, at least about 80% of the dose of PTHin the microprotrusion array is confined to the end portion (tip) ofeach microprotrusion, wherein the “tip” intends that portion of amicroprotrusion that is intended to penetrate the stratum corneum. Inother embodiments, at least about 85% and at least about 90% or 95% or98% of the dose of PTH in the microprotrusion array is confined to theend portion (tip) of each microprotrusion.

In one embodiment, to prepare a PTH-containing microarray as providedherein, the solution comprising PTH is cast so that it fills thecavities of a mold. This solution is then dried. A further solution witha lower or zero concentration of active, constituting a second layer, isthen cast over the solution or layer comprising the PTH. The polymersused in the first layer are preferably not soluble in the solvent usedfor the second layer. The second layer preferably uses a differentpolymer or polymers from the ones used in the first layer. Thisprocedure may produce an array having two layers, and in which themicroprojections are enriched in active. In such an array, the activewould not be expected to substantially diffuse into the second layer.

The second layer may comprise any of a number of polymers such ascellulose acetate butyrate, cellulose acetate, cellulose acetatepropionate, ethyl cellulose, nitrocellulose, hydroxypropyl methylcellulose phthalate, polystyrene, polyacrylates (such asacrylate/octylacrylamide copolymers, Dermacryl® 97), polymethacrylates(such as Eudragit® E, RL, RS, L100, S100, L100-55), or poly(hydroxylalkanoates). Preferably the second layer comprises a biocompatible,biodegradable polymer(s) such as PLA, PGA, PLGA, polycaprolactone andcopolymers thereof. A particularly preferred polymer is thewater-insoluble polymer, PLGA.

Preferably, where the first layer is cast in an aqueous solvent, thesecond layer comprising the upper portion of the microprojection, and incertain instances, the base, is cast in an organic solvent. Preferredsolvents for preparing and casting the second layer include alcohols,for example isopropyl alcohol and ethanol, and esters, for example ethylacetate, heptane, or propyl acetate, or other solvents such asacetonitrile, dimethylsulfone (DMSO), N-methylpyrrolidone (NMP), orglycofurol.

As described above, the microprojections of the array preferably detachfrom the array following insertion into the skin. In one embodiment,only a tip portion of each microprojection detaches from the microarray.In one embodiment, detachment of all of a microprojection or of only aportion of each microprojection is achieved by degradation ordissolution of the material from which that microprojection or thatportion of the microprojection is manufactured. Advantages related tothis feature include the elimination of sharp disposal requirements,elimination of needle stick injury, and the like.

Detachable microprojections may be prepared using a number ofapproaches. A layered approach, for example, may be used in which thearray is composed of multiple layers, and a layer comprising theattachment areas of the microprojections to the array is more readilydegradable or dissolvable than the other layers, such that uponactivation, the drug-containing tip of the microprojection is detachedfrom the upper portion of the microprojection or from the base,depending upon the specific configuration. For example, the layercomprising the attachment areas may be more rapidly hydrated than theother layers.

The array may also comprise a polymer or polymer blend havingbioadhesive properties which within a certain range of moisture willhave higher adhesive strength the greater the moisture. In oneembodiment, the multilayer array is one in which the layer or layers inwhich the microneedles principally lie possess bioadhesivecharacteristics.

Exemplary polymers with bioadhesive characteristics include suitablyplasticized polyvinyl alcohol and polyvinylpyrrolidone. An extensivediscussion of a class of bioadhesive polymer blends is found in U.S.Pat. No. 6,576,712 and U.S. Published Patent Applications Nos.2003/0170308 and 2005/0215727, which are incorporated by reference fortheir teaching of bioadhesive polymer blends and adhesion testing.Preferable bioadhesive polymers are those which possess hydrogen-bondedcrosslinks between strands of the primary polymers. These crosslinks maycomprise a comparatively small molecule which forms hydrogen bonds totwo primary polymer strands. It is believed that certain sugars may actas a small molecule crosslinker in this manner with particular primarypolymers such as polyvinyl alcohol, dextran and tetrastarch.

The microprojection arrays may also include one or more additives ormeasures to retard or diminish microorganism growth. For example, themicroprojection arrays may be packaged in a sealed, low oxygenenvironment to retard aerobic microorganisms and eventually destroytheir viability. The arrays may also be packaged in a low moistureenvironment to dehydrate microorganisms. Alternatively, apharmaceutically acceptable antibacterial agent may be included in theformulation or the packaging. Examples of such agents are benzalkoniumchloride, benzyl alcohol, chlorbutanol, meta cresol, esters of hydroxylbenzoic acid, phenol, thimerosal, and silver or silver salts. As afurther alternative, a surfactant or detergent can be added to thecasting formulations to disrupt the cell membrane of potentialmicroorganisms; alternatively, a desiccant may be added to thepackaging.

Antioxidants may also be added to the formulation, for example, toprotect the PTH from oxidation. Exemplary antioxidants includemethionine, cysteine, D-alpha tocopherol acetate, DL-alpha tocopherol,ascorbyl palmitate, ascorbic acid, butylated hydroxyanisole, butylatedhydroxyquinone, butylhydroxyanisole, hydroxycomarin, butylatedhydroxytoluene, cephalin, ethyl gallate, propyl gallate, octyl gallate,lauryl gallate, propylhydroxybenzoate, trihydroxybutyrophenone,dimethylphenol, ditertbutylphenol, vitamin E, lecithin, andethanolamine. Chelating agents, e.g. ethylenediaminetetraacetic acid(EDTA), may also be added to the formulation to protect PTH fromoxidation.

Formulations

PTH-containing formulations used to prepare the instant microprotrusionarrays are described generally above. The drug-containing formulation,sometimes referred to herein as the drug-in-tip or DIT formulation,contains an amount of PTH sufficient to provide a therapeuticallyeffective amount in the final microprojection array product. Generally,the amount of PTH ranges from about 10-500 μg per dosage unit, or fromabout 10-250 μg per dosage unit, or from about 10-100 μg per dosageunit.

The PTH is contained in a water-soluble polymer matrix. Preferably, thematrix comprises one or more water-soluble polymers. One preferredwater-soluble polymer is a polysaccharide, such as the exemplarypolysaccharide, dextran. The dextran preferably possesses a molecularweight ranging from about 1 to about 150 kilodaltons, or from about 40to about 100 kilodaltons. Representative dextrans possess each of thefollowing molecular weights: 1 kilodaltons, 10 kilodaltons, 20kilodaltons, 40 kilodaltons, 70 kilodaltons, and 75 kilodaltons.Generally, dextran is present in the final end portion of themicroprojections in an amount greater than that of any of the othercomponents. Typically, the amount of polysaccharide, such as dextran 70,ranges from about 1 percent by weight to about 90 percent by weight,more preferably from about 20 percent by weight to about 70 percent byweight, still more preferably from about 35 percent by weight to about70 percent by weight, of the DIT formulation, based upon dry weight(i.e., the layer after solvent removal). The amount of PTH contained inthe layer will of course vary, based upon the amount of PTH to beadministered per dosage unit. Generally, the amount contained in thefinal end portion ranges from about 1 percent by dry weight to about 50percent by dry weight, more preferably from about 5 percent by dryweight to about 25 percent by dry weight, still more preferably fromabout 7.5 percent by dry weight to about 10 percent by dry weight. Theother major component of the DIT layer is the sugar alcohol, sorbitol.Sorbitol is typically present in an amount less than dextran.Illustrative ranges of sorbitol content are from about 1 percent byweight to about 50 percent by weight, or from about 10 percent by weightto about 35 percent by weight, of the formulation. Thus, the maincomponents forming the water-soluble polymer matrix are PTH, dextran,and sorbitol. Additional lesser components include the buffers histidineand histidine hydrochloride, as well as any PTH counterions, ifapplicable.

Generally, the casting solutions or precursor solutions to the final DITlayer are prepared to have a total solids content ranging from about 1%solids to about 50% solids, or from 15% solids to about 45% solids,where representative solids contents include 5, 10, 15, 20, 25, 30, 35,40, 45 and 50% solids.

The upper portion or layer of the microprojections and base typicallycomprise at least one water-insoluble polymer and are substantiallyabsent PTH, to provide an array having microprojections that arePTH-enriched in comparison to the upper portion and base portions of thearray. One preferred type of water-insoluble polymer is PLGA, and inparticular, poly(lactic acid-co-glycolic acid), having a lactide toglycolide ratio of 75/25. Materials having other DL-lactide to glycolideratios may also be used, such as 50:50, 65:35, 85:15, or PLA by itself.Preferably, the PLGA is ester-terminated. Such polymers are availablefrom Durect (Cupertino, Calif.).

Description of an exemplary PTH formulation as described above isprovided in Example 9.

Transdermal Delivery Device

In one or more embodiments, the microprojection array forms part of afinal transdermal delivery system or product. The product typicallycomprises the microprotrusion array according to any one or more of theembodiments provided herein, and an array support member (also referredto herein as a microprojection-holding member). The array support member(or microprojection-holding member) is typically affixed or affixable tothe base of the microprotrusion array at the surface opposite themicroprotrusions. One such exemplary microprojection-holding member is aplunger as described in Example 10.

The product may further comprise an applicator assembly that comprises ahousing and an energy storage member effective to activate the device.See, e.g., FIGS. 1 and 2 , along with Example 10.

As described above, such an applicator suitable for use is illustratedin FIGS. 1 and 2 , where an applicator 180 is shown fully assembled inFIG. 1 and in exploded view in FIG. 2 . An outer housing 182 isdimensioned to contain an energy-storage member 183 and amicroprojection-holding member 184 which holds a microprojection array(not shown in the figures). In storage and prior to use,microprojection-holding member 184 is held in place by two platforms inhousing 182, such as platform 196, against which a projection member,such as members 185, 187 in member 184, engages. When it is desired toactivate the device, a user twists member 184 (e.g., with thumb andforefingers gripping projection members 185, 187) so that it is nolonger over the platforms and restrained by them. When that twistingoccurs, energy-storage member 183 moves downward pressing themicroprojection-holding member in a downward direction to contact themicroprojection array against the skin.

The applicator of FIGS. 1 and 2 is further provided with an optional setof components for adapting to skin, in this case an adapter 190, a snapring 186, and an extender 188. In addition, FIG. 1 shows an optionaladhesive 192 and an optional release liner 194. An optional safetyfeature to prevent inadvertent or accidental actuation of the applicatorcan also be provided. In one embodiment, a pin 197 is removably insertedthrough a cavity in microprojection holding member 184 prior to use. Theapplicator may be simplified and adapted to reduce the number of parts.To enable the applicator for actuation, a user pulls pin 197 from itsretaining position as shown in FIG. 1 to permit a user to activate theapplicator by the twisting motion described above. Variousconfigurations, components, and embodiments of a microprojectionarray-based transdermal delivery system suitable for administering PTHaccording to the methods provided herein are described in co-owned U.S.Provisional Patent Application No. 60/331,175, filed on May 4, 2010, theentire content of which is expressly incorporated herein by reference.It will be appreciated that the applicator described herein is merelyexemplary, and that any applicator that achieves penetration of themicroprojections into the skin of a user is contemplated for use in theclaimed methods.

Product components may optionally be provided as part of a kit, e.g.,for assembly prior to actuation and use, or alternatively, in assembledform. See, e.g., FIG. 1 . For example, one such kit may contain amicroprojection array along with an array support member, where thearray support member is affixable or affixed to the base of themicroprotrusion array at the surface opposite the microprotrusions.

The kit may optionally further comprise an applicator assemblycomprising a housing in which the array support member andmicroprotrusion array can be disposed, combined with an energy storagemember that is movable between first and second configurations (e.g., aresting position and a position in which the microprojection-holdingmember is extended in a downward direction to contact themicroprojection array against the skin as described above). In oneparticular embodiment, the energy storage member is a spring.Optionally, the applicator assembly comprises fasteners to temporarilyhold together the housing and the energy storage member.

The kit may also comprise various components of the final product asdescribed above to be assembled prior to use, where any of theindividual or combinations of components may be provided in primarypackaging, and optionally further contained in secondary packaging.

Pharmacokinetics

The microprojection array described herein was used to administertransdermally hPTH (1-34) to healthy human subjects. As a comparator,hPTH (1-34) was also administered subcutaneously to a healthy group ofhuman subjects. Details of this study are provided in Example 11, andthe resulting data are presented in FIGS. 3-8 and in Table 1, now to bedescribed.

In this study, a microprojection array was prepared as detailed inExample 9 and inserted into an applicator-array assembly to form atransdermal delivery system, as described in Example 10. The systemdescribed in Examples 9 and 10 is referred to herein, and in thedrawings, as “MicroCor® hPTH (1-34)” or more simply, “MicroCor®”. Thedelivery system was designed to deliver a systemic dose of hPTH (1-34)across the stratum corneum barrier layer of the skin upon activation ofthe applicator to deploy an array of microstructures causing the arrayof microstructures to penetrate the stratum corneum. In this study, twodose levels were administered via the transdermal delivery system, 32 μghPTH (1-34) and 64 μg hPTH (1-34) (32 μg hPTH (1-34)×2). Subjectsreceived these doses by applying the transdermal microneedle deliverysystem MicroCor® device containing the indicated amount of hPTH in thedistal tips of the microneedles in the array to an abdominal site, andleaving the device in place for five (5) minutes. The comparatortreatment (the commercial hPTH product known as Forteo®) wassubcutaneously administered via injection into the abdominal wall at adose of 20 μg. Blood samples were drawn at designated times and analyzedfor hPTH concentration. The pharmacokinetic data is summarized in FIGS.3-8 and in Table 1.

FIG. 3 is a plot of average hPTH (1-34) plasma concentration (pg/mL)versus time, in hours, for subjects treated hPTH administered via thetransdermal microneedle delivery system (under the tradename MicroCor®)at a dose of 32 μg (open squares) and 64 μg (open diamonds) or viasubcutaneous injection (Forteo®) at a dose of 20 μg (open triangles).Administration of PTH from the microprojection delivery system whereinthe PTH was contained within a dissolvable polymer matrix from which themicroprojections, or at least the tips of each microprojection, wasfabricated, achieved a rapid onset to maximum plasma concentration.Specifically, and with reference to FIGS. 5-6 , for the 32 μg dose, amaximum plasma concentration (180 μg/mL) was reached in about 8 minutes,and for the 64 μg dose, a maximum plasma concentration (336 μg/mL) wasreached in 7.4 minutes after application of the system to the skin.Subcutaneous injection of a 20 μg dose of PTH, in contrast, achieved itsmaximum concentration (85 μg/mL) 26 minutes post injection.

Accordingly, in one embodiment, a method for administering PTH to ahuman subject is provided, by contacting the skin of the subject with amicroprotrusion array containing a dose of PTH and causing all or aportion, preferably a majority, of the microprotrusions to penetrate thestratum corneum. Entry of the microprotrusions into the skin achievesdelivery of the PTH to the subject, wherein the time to maximum plasmaconcentration (Tmax) is less than about 20 minutes, more preferably Tmaxis achieved in about 15 minutes or less, more preferably in less thanabout 12 minutes, still more preferably in less than about 10 minutes,more preferably in less than about 9 minutes.

With continuing reference to FIG. 3 and additionally to FIG. 7 , it canalso be seen that administration of PTH from the microprojectiondelivery system described herein, in addition to a rapid (e.g., about 10minutes or less) onset to maximum plasma concentration, a rapidelimination rate is also achieved. The elimination half life (T_(1/2)),calculated in accord with standard equations and methods in the art andgenerally reflective of the time for the plasma concentration to fall tohalf of its original value, was 37 minutes for the 32 μg dose of hPTHadministered via the transdermal microneedle delivery system. Theelimination half life was 52 minutes for the 20 μg dose of hPTHadministered via subcutaneous injection.

Accordingly, in one embodiment, a method for administering PTH to ahuman subject is provided, by contacting the skin of the subject with amicroprotrusion array containing a dose of PTH and causing all or aportion, preferably a majority, of the microprotrusions to penetrate thestratum corneum. Entry of the microprotrusions into the skin achievesdelivery of the PTH to the subject, wherein the elimination half life ofPTH is less than about 45 minutes, and more preferably is 40 minutes orless. In one embodiment, the PTH when administered via the microneedledelivery system described herein, wherein PTH is contained in awater-soluble polymer matrix in at least the tip portions of eachmicroprojection in an array, provides a time to maximum plasmaconcentration (Tmax) of less than about 20 minutes, more in about 15minutes, 12 minutes, 10 minutes or 9 minutes or less, and an eliminationhalf life of less than about 45 minutes, and more preferably 44, 43, 42,41 or 40 minutes or less.

In another embodiment, PTH administered in accord with themicroprotrusion array described herein provides a maximum plasmaconcentration of greater than about 100 μg/mL, more preferably of 125,130, 135, 140, 145, 150, 155, 160, 165, 170, or 175 μg/mL, for a dose of32 μg PTH, in less than about 20 minutes, about 15 minutes, about 12minutes, about 10 minutes or about 9 minutes, and an elimination halflife of less than about 45 minutes, and more preferably 44, 43, 42, 41or 40 minutes or less.

In another embodiment, a method for administering PTH to a human subjectis provided, by contacting the skin of the subject with amicroprotrusion array containing a dose of PTH and causing all or aportion, preferably a majority, of the microprotrusions to penetrate thestratum corneum. Entry of the microprotrusions into the skin achievesdelivery of the PTH to the subject, wherein the time to maximum plasmaconcentration (Tmax) is 50% lower (shorter), more preferably 55%, 60%,65% or 70% less than the time to maximum plasma concentration achievedwith the same, or lower dose, of PTH delivered via subcutaneousinjection. In another embodiment, the method of PTH administration via atransdermal microneedle array in accord with that described hereinprovides delivery of PTH to the subject such that the elimination halflife is at least about 15%, 20%, 22% or 25% faster than the eliminationhalf life achieved with the same, or lower dose, of PTH delivered viasubcutaneous injection.

Dose-normalized area under the curve values in pg*min/mL*μg werecalculated from the plasma concentration data, and are presented in FIG.4 . The AUC values for the exemplary microprotrusion array-based hPTHtransdermal delivery system was approximately 48% lower than the AUCvalue for hPTH administered subcutaneously via injection. The lower AUCof the drug when administered via microneedles transdermally isindicative of the fast elimination half life, and supportive of thismethod of delivery being able to achieve the desirable pulsatiledelivery profile, wherein a pulse of drug is provided to the system witha rapid onset to maximum blood concentration and a fast eliminationhalf-life of drug.

TABLE 1 Pharmacokinetic Results MicroCor ® MicroCor ® Parameter 32 μg 64μg Forteo ® AUC/Dose 220 (n = 15) 229 (n = 16) 429 (n = 16)(pg*min/mL*μg) C_(max) 180 (n = 16) 336 (n = 16)  85 (n = 16) (pg/mL)T_(max) (minutes)  8.1 (n = 16)   7.4 (n = 16)  26.2 (n = 16) Elimination 37.1 (n = 16)   52 (n = 16)  52 (n = 16) Half-Life, T_(1/2)(minutes)

As can be seen from the data summarized in Table 1, relative tosubcutaneously injected PTH, delivery transdermally via an array ofmicroprojections exhibits rapid pharmacokinetic properties such as ashorter T_(max), a higher C_(max), and a shorter elimination half life,T_(1/2). Absorption of hPTH (1-34) occurred more rapidly with themicroprojection transdermal delivery relative to the subcutaneousdelivery (Forteo®), as illustrated by the higher dose-normalized C_(max)value and the smaller T_(max) values for both microprojectiontransdermal delivery (MicroCor®) treatments.

FIG. 8 presents the pharmacokinetic data from the study of Example 11 ina different way, to illustrate the pulsatile delivery profile achievedwith the microneedle array delivery system described herein. In FIG. 8 ,the plasma concentration value at each time point was normalized by themaximum concentration value achieved by each of the three treatmentregimens: 32 microgram and 64 microgram doses of PTH delivered by themicroprotrusion array and the 20 microgram dose delivered viasubcutaneous injection. The Cmax normalized plasma concentration data isplotted against time, in hours. The time to achieve Cmax of well under30 minutes when PTH is delivered transdermally from the microneedlearray compared to the time to reach Cmax of greater than 30 minutes whenadministered subcutaneously is evident. The faster elimination of thedrug after reaching Cmax when delivered transdermally from themicroneedle array is also readily seen when the data is presented asshown in FIG. 8 , by comparing the slopes of the lines during theelimination phase—i.e., at a time after Cmax.

In summary, relative to subcutaneous administration, the exemplarymicroprojection array-based PTH products described herein exhibit rapidpharmacokinetic properties. Such properties (relative to subcutaneousinjection) include a shorter Tmax, a higher Cmax, and a shorterelimination half life, T_(1/2). Ideally, administration using amicroprojection array-based PTH product is effective to achieve a Tmaxvalue that is at least about 2 times less, or at least about 3 timesless, or at least about 4, or 5, or 6, or 7 times or more less than thatachieved by SC administration of the same PTH moiety, preferably basedupon normalized Cmax values. Absorption of hPTH (1-34) occurs morerapidly when delivered with the microprojection array-based deliverysystem when compared to delivery via subcutaneous injection (i.e., hPTHproduct Forteo®), as illustrated by the higher dose-normalized C_(max)values and the faster T_(max) values for both the high and low dosemicroprojection array-based treatments. The elimination half-life basedupon microprojection array-based PTH treatment was also less than withsubcutaneously administered PTH (Forteo®). Moreover, microprojectionarray-based treatment is more effective in achieving the desiredpulsatile delivery profile of PTH (i.e., rapid on set and rapid offsetafter reaching Cmax), as can be seen in FIGS. 3 and 8 .

The transdermal microprojection array delivery systems were analyzedafter use, to assess residual PTH content in the microprojection array.Analysis for residual PTH in the arrays following application to asubject for delivery of the drug, revealed that, on average, about 85%of drug was delivered from the microprojection array device (i.e., 85%drug delivery efficiency, data not shown). Accordingly, in oneembodiment, the method includes providing for use in the method amicroprojection array capable of delivery at least about 55%, or atleast about 60%, or at least about 65%, or at least about 70%, or atleast about 75%, or at least about 80%, or at least about 85% of thetotal PTH dose in the array when applied to the skin of the patient forthe desired amount of time. In the studies conducted above, themicroarray was in contact with the skin for 5 minutes, however it willbe appreciated that the microprojection array-delivery system can beapplied to a skin site for times other than the 5 minutes utilized inthe present study. In one embodiment, the system is maintained on theskin for no more than 15 minutes, or for no more than 10 minutes, oreven for no more than 5 minutes. That is to say, the microprojectionarray is maintained on the skin for no more than about 15 minutes, or 14minutes, or 13 minutes, or 12 minutes, or 11 minutes, or 10 minutes, or9 minutes, or 8 minutes, or 7 minutes, or 6 minutes or even 5 minutes.Although any of a number of skin sites may be used for application ofPTH such as the thigh, arm, etc., one preferred skin site is theabdomen.

A skilled artisan will also appreciate that delivery efficiency based onresidual analysis of the microprojection array post-use is but onemeasure to characterize the device. The microprojection array can alsobe characterized by the percentage of total dose delivered by themicroprojection array, determined for example based on pharmacokineticparameters and the total amount of drug loaded into the microprojectionarray. This value may differ from a residual analysis since some of thedrug delivered may be degraded by enzymes in the skin or not reachsystemic circulation for other reasons. In one embodiment, the methodfor administering PTH to a human subject comprises contacting the skinof the subject with a microprotrusion array containing a dose of PTH andcausing all or a portion, preferably a majority, of the microprotrusionsto penetrate the stratum corneum. The microprotrusions in the array areleft in contact with the skin for a period of time. Application of thedevice to the skin in accord with the method delivers at least about40%, 45%, 50%, 55% or 60% of the total PTH dose in the microprotrusionarray into systemic circulation of the subject. In another approach, thedelivery efficiency of the microprojection array is determined based oncomparing the pharmacokinetic parameters, and in particular AUC, topharmacokinetic parameters achieved from a subcutaneously injected doseof PTH.

Methods of Use

The methods, kits, microprojection arrays and related devices describedherein may be used for treating any condition receptive to treatmentwith PTH. For instance, the PTH-containing microprojection arrays may beused to deliver PTH for treatment of osteoporosis, osteopenia,periodontal disease, and in particular, periodontal disease associatedwith alveolar bone loss. The PTH-containing microprojection arrays arealso contemplated for use in healing bone fractures, improving bonefracture healing rates and for reducing risk of fracture in at riskpersons.

More particularly, the methods, kits, microprojection arrays and relateddevices described herein may be used for (i) treating postmenopausalwomen with osteoporosis at high risk for fracture, (ii) increasing bonemass in men with primary or hypogonadal osteoporosis at high risk forfracture, (iii) treatment of osteoporosis in men and women withosteoporosis associated with sustained glucocorticoid therapy at highrisk for fracture, and (iv) treatment of osteoporotic patients who havefailed or are intolerant of other available osteoporosis therapies.

It is to be understood that while the invention has been described inconjunction with the preferred specific embodiments thereof, theforegoing description is intended to illustrate and not limit the scopeof the invention. Other aspects, advantages, and modifications withinthe scope of the invention will be apparent to those skilled in the artto which the invention pertains.

All patents, patent applications, and publications mentioned herein arehereby incorporated by reference in their entireties. However, where apatent, patent application, or publication containing expressdefinitions is incorporated by reference, those express definitionsshould be understood to apply to the incorporated patent, patentapplication, or publication in which they are found, and not necessarilyto the text of this application, in particular the claims of thisapplication, in which instance, the definitions provided herein aremeant to supersede.

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how toimplement the invention, and are not intended to limit the scope of whatthe inventors regard as their invention. Efforts have been made toensure accuracy with respect to numbers (e.g., amounts, temperature,etc.) but some errors and deviations should be accounted for. Unlessindicated otherwise, parts are parts by weight, temperature is in ° C.and pressure is at or near atmospheric.

Example 1 General Process for Array Casting

A clean mold is placed in a mold folder. The mold is then placed in aPetri dish and a small amount of formulation, for example, 200 μl, isplaced on the mold. An illustrative formulation such as those describedherein is applied. The formulation is spread manually over the moldusing a transfer pipette with a trimmed tip. The formulation is thenvortexed, for example, for five seconds, using a commercial vibratinginstrument. The mold containing formulation is placed in a pressurevessel under 1 atm for about 1 minute. Pressure is released, and themold placed in an incubator at 32° C., for about 1 hr. The array is thendemolded, for example, using double-sided adhesive tape, and optionallyattached to a backing.

Example 2 General Process for Casting Two-Layer Arrays

Following the drying step of Example 1, an additional layer is cast onthe mold using similar procedures. An exemplary composition, e.g.,containing 75 μl of 20 wt % Eudragit® EPO in a 3:1 mixture of ethanoland isopropyl alcohol is cast onto the mold. The additional layer may bespread out, for example, using a glass slide. The mold containing theadditional layer is placed in a pressure vessel and pressurized at 1 atmfor 2 minutes. The pressure is released and the mold is allowed to dryin the pressure vessel for an additional five minutes, withoutdisturbing. The mold is again dried in the incubator for 1 hr at 32° C.,and then demolded.

Example 3 Casting Two-Layer Arrays

A microprojection array with two layers is typically prepared by thefollowing steps.

STEP 1. CASTING A SOLUTION COMPRISING AN ACTIVE AGENT, POLYMER, ANDPOSSIBLY OTHER COMPONENTS IN A MOLD. The clean mold is placed in a moldholder. A small amount of formulation, for example, 75 μL, as a dropleton the mold, is dispensed by placing a cover slip on top of the dropletto help spread the liquid onto the entire surface of the mold. Anexemplary wet formulation contains, for example, 15% human parathyroidhormone 1-34 fragment (hPTH1-34), 65% dextran 70 and 20% sorbitol, in ahistidine buffer solvent with a total solids content of 30% as appliedto the mold. The loaded mold (i.e., containing drug formulation) isplaced in a pressure vessel under about 50 psi for about 30 seconds.Pressure is then removed. The excess formulation is wiped with asilicone or metal wiper with the interference between wiper edge andsurface of mold about 1-10 mils. The mold is placed in an incubator at atemperature of 32° C., for about half an hour. After incubating, the dryformulation contains 5% human parathyroid hormone 1-34 fragment(hPTH1-34), 21% dextran 70 and 7% sorbitol, with histidine and histidinehydrochloride also present.

STEP 2. CASTING AN ADDITIONAL LAYER ON TOP OF THE FIRST LAYER IN THEMOLD. The mold with drug-containing layer cast is removed from thedrying oven, and any residue of dry formulation left on the base of themold is removed by tape strip using a 3M 1516 single-sided adhesive.Approximately 150 μl of “backing” or upper layer/base solutioncontaining poly(lactic acid-co-glycolic acid) (PLGA) with an L/G ratioof 75/25 in acetonitrile is placed on the mold (atop the firstdrug-containing formulation). A thin film is cast using a wiper with theclearance between edge of the wipe and the surface of the mold about10-20 mil. The mold is then placed into a pressure vessel under 10-30psi with controlled venting for about 5 min. The mold is further driedat room temperature for about 30 min. The array may then be demolded,for example using double-sided adhesive tape, and optionally attached toa polyethylene terephthalate film as backing.

Example 4 Solvent-Cast Microprojection Arrays Containing hPTH (1-34)

Microprojection arrays were prepared according to the general proceduresdescribed above. The following table provides the relative amounts ofwater-soluble matrix components and active agent, along with the percentsolids content of the resulting exemplary casting solutions.

TABLE 4-1 Solids in hPTH casting Polymer Sugar (1-34) solution Ex. #Type Wt % Type Wt % Wt % Wt % B1 PVA 52.6 Sucrose 26.3 21.1 22.8 B2 PVA46.2 Sucrose 23.1 30.7 26 B3 Dextran 70 67.5 Sorbitol 14 18.5 33 B4Dextran 70 64.9 Sorbitol 19.5 15.6 30.8 B5 Dextran 40 67.5 Sorbitol 1418.5 33 B6 Dextran 40 64.9 Sorbitol 19.5 15.6 30.8 B7 Tetrastarch 67.5Sorbitol 14 18.5 33 B8 Tetrastarch 64.9 Sorbitol 19.5 15.6 30.8 B9*Dextran 70 64.8 Sorbitol 19.3 15.5 31.2 *ca. 0.4 wt % of methionine wasadded to the formulation as an antioxidant agent.

Based on the above, it can be seen that a wide variety of formulationscan be prepared for use in forming a microprojection arrays for deliveryof hPTH through the skin.

Example 5 Polymeric Solutions for Casting “Backing” or Upper Layers ofMicroneedle Arrays

For arrays comprising an upper microprotrusion portion or layer proximalto the base of the array and placed atop the water soluble polymer/h PTHtip layer), different polymer formulations were used. The backing layer(which in this embodiment comprises the upper portion of themicroprotrusion proximal to the base and the base itself) comprises oneor more water-insoluble polymers. The polymer solutions were typicallyprepared by dissolving the polymers in a solvent or solvent mixture atroom temperature with a polymer concentration ranging from about 15-30%by weight.

The details of the illustrative polymer solutions used for casting thebacking layer of the microneedle arrays are summarized in the tablebelow.

TABLE 5-1 Polymer Solvent Ex. # Type Wt % Type Wt % C1 Eudragit EPO 10020 Ethanol/IPA 80 C2 Eudragit EPO 100 30 Ethanol/IPA 70 3/1 C3 EudragitEPO 20 Ethanol/IPA 80 100/PVP (1:1) 3/1 C4 PLGA (75/25) 10 Ethyl acetate90 C5 PLGA (75/25) 15 Ethyl acetate 85 C6 PLGA (75/25) 15 Acetonitrile85 C7 PLGA (75/25) 20 Acetonitrile 80 C8 PLGA (75/25) 30 Acetonitrile 70C9 PLGA (65/35) 20 Acetonitrile 80 C10 PLA 20 Acetonitrile 80 C11Polycaprolactone 20 Acetonitrile 80

In the table above, the following abbreviations are used:Polyvinylpyrrolidone (PVP); poly(lactic acid-co-glycolic acid) (PLGA)(L/G ratio 75/25, 65/35); poly(lactic acid) (PLA); and isopropyl alcohol(IPA).

Example 6 Casting Microneedle Arrays with Three Layers

A microneedle array with three layers is prepared as follows.

1) Casting a non-drug containing tip layer (end portion distal to base)in the mold. The clean mold is placed in a mold holder. A small amount(200 μL) of formulation solution absent drug is dispensed as a dropleton the mold. One such exemplary formulation contains, for example, 23%dextran 70, 10% sorbitol in histidine buffer solvent, such that theformulation has, e.g., a 30% solids content as applied. The moldcomprising formulation is placed in a pressure vessel under ca. 50 psifor about 30 seconds. Pressure is then released. Any excess formulationis wiped with a silicone or metal wiper with the interference betweenwiper edge and surface of the mold at about 1-10 mils. The mold isplaced in an incubator at a temperature of 32° C., for about half anhour.

2) Casting drug containing layer in the mold. After step 1) above, asmall amount of formulation, for example, 75 μL, is dispensed as adroplet on the mold. A cover slip is placed on top of the droplet to aidin spreading the liquid onto the entire surface of the mold. One suchillustrative formulation may contain, for example, on a dry weigh basis5% wt human parathyroid hormone 1-34 fragment (hPTH (1-34)), 21% wtdextran 70, 7% wt sorbitol. The wet casting formulation utilizeshistidine buffer as the solvent, such that the formulation has, forexample, a 30% solids content as applied. The mold containing is thenplaced in a pressure vessel under ca. 50 psi for about 30 seconds.Pressure is then released. The excess formulation is wiped with asilicone or metal wiper with the interference between wiper edge andsurface of mold about 1-10 mils. The mold is placed in an incubator at atemperature of 32° C., for about half an hour.

3) Casting the backing layer on top of the drug-containing layer. Afterstep 2) above, about 150 μL of backing solution (upper layer portion)comprising poly(lactic acid-co-glycolic acid) (PLGA) with a L/G ratio of75/25 in acetonitrile is placed on the mold (on top of thedrug-containing layer). A thin film is cast using a wiper with theclearance between edge of the wipe and surface of the mold about 10-20mil. The mold is then placed into a pressure vessel under 10-30 psi withcontrolled venting for about 5 min. The mold is further dried at roomtemperature for about 30 min. The array is then demolded, for exampleusing double-sided adhesive tape, and optionally attached to apolyethylene terephthalate film as backing.

Example 7 Casting Arrays for Sustained Release of Drug Substance fromthe Array

A microneedle array for sustained release of drug substance from thearray is prepared in the following steps.

1) Casting a drug-containing layer for sustained release of drugsubstance. A clean mold is placed in a mold holder. A small amount(e.g., 75 μL) of aqueous solution containing, e.g., hPTH (1-34),components for a polymeric matrix such as polyethyleneglycol-co-poly(lactic acid-co-glycolic acid) (PEG-PLGA) copolymer, andexcipients such as sucrose or sorbitol, is dispensed into the mold. Thepolymeric matrix is generally amphiphilic in nature, where thehydrophobic segment(s) of the polymer are effective to control therelease of drug substance. Exemplary formulations of this type aredescribed in the table below. The liquid formulation is spread manuallyon the surface of the mold with a glass cover slip. Theformulation-loaded mold is placed in a pressure vessel under ca. 50 psifor about 30 seconds. Pressure is then released. Excess formulation iswiped with a silicone or metal wiper with the interference between wiperedge and surface of the mold about 1-10 mils. The mold is placed in anincubator at room temperature for about half an hour.

The following table provides the details of representative aqueoussolutions used to form this type of microneedle array comprising drugsubstance hPTH, a polymeric matrix, and excipients.

TABLE 7-1 Solids in hPTH casting Polymer Excipients (1-34) solution Ex.# Type Wt % Type Wt % Wt % Wt % D1 PEG-PLGA 50 Sucrose 35 15 10(50/50(65/35)) D2 PEG-PLGA 45 Sucrose 40 15 10 (50/50(65/35)) D3PEG-PLGA 45 Sucrose 40 15 20 (50/50(65/35)) D4 PEG-PLGA 55 Sucrose 35 1010 (50/30(65/35)) D5 PEG-PLGA 55 Sucrose 35 10 10 (50/30(65/35)) D6PEG-PLGA 55 Sorbitol 35 10 10 (50/30(65/35)) D7 PEG-PLGA 45 Sorbitol 4015 10 (50/50(65/35)) D8 Pluronic F68 50 Sucrose 35 15 25 D9 PluronicF127 50 Sucrose 35 15 15 D10 Pluronic F68 50 Sorbitol 35 15 25 D11Pluronic F127 50 Sorbitol 35 15 15

In the table above, PEG-PLGA denotes a blend of polyethylene glycol andpoly(lactic acid-co-glycolic acid).

2) Casting a dissolvable layer on top of the drug-containing layer inthe mold. After step 1) above, a small amount of formulation, forexample, 25 μL, is placed as a droplet on the mold, and a cover slip isplaced on top of the droplet to spread the liquid onto the entiresurface of the mold. For example, an illustrative wet formulationcontains 70% Dextran 70, and 30% sorbitol, in histidine buffer solvent,such that the formulation contains, for example, 30% solids content asapplied. The drug-polymer matrix loaded mold is placed in a pressurevessel under ca. 50 psi for about 30 seconds. Pressure is then released.Excess formulation is wiped with a silicone or metal wiper with theinterference between wiper edge and the surface of the mold about 1-8mils. The mold is placed in an incubator at a temperature of 32° C., forabout half an hour.

3) Casting a backing layer on top of the dissolvable layer in the mold.Following step 2) above, approximately 150 μL of backing solution (upperportion layer) containing poly(lactic acid-co-glycolic acid) (PLGA) witha L/G ratio of 75/25 in acetonitrile is placed on the mold (on top ofthe dissolvable layer) and a thin film is cast using a wiper with theclearance between edge of the wipe and surface of mold about 10-20 mil.The mold is then placed into a pressure vessel under 10-30 psi withcontrolled venting for about 5 min. The mold is further dried at roomtemperature for about 30 min. The array is demolded, for example usingdouble-sided adhesive tape, and optionally attached to a polyethyleneterephthalate film as backing.

Example 8 hPTH (1-34) Stability in Dry Films Made with MicroneedleCasting Formulations

Dry films of microneedle casting formulations were prepared usingprocess conditions similar to those for casting microneedle arrays toevaluate the stability of hPTH (1-34 fragment) in the dried form. About200 μL of liquid formulation was placed in an Eppendorf tube. Theformulation was spread into a thin film in the inside wall of the tube,then dried at 32° C. for 30 min, and then further dried under vacuum atroom temperature overnight. The dry films inside the Eppendorf tube werepackaged in a polyfoil bag and stored at different temperatures fordifferent durations. The purity of the hPTH (1-34) was analyzed by bothreverse phase HPLC (rp-HPLC) and size exclusion HPLC (sec-HPLC). Thedetails of the formulations are indicated in Table 8-1 below.

The following table provides details of the formulations used to formdry films containing hPTH as the active agent.

TABLE 8-1 Solids in hPTH casting Polymer Sugar (1-34) solution Ex. #Type Wt % Type Wt % Wt % Wt % F1 PVA 52.6 Sucrose 26.3 21.1 22.8 F2Dextran 70 64.9 Sorbitol 19.5 15.6 30.8 F3 Tetrastarch 64.9 Sorbitol19.5 15.6 30.8 F4* Dextran 70 64.1 Sorbitol 19.4 15.4 31.2 *ca. 0.4 wt %of methionine was added to the formulation as an antioxidant agent.

Table 8-2 below illustrates the chemical purity as determined by rp-HPLCof the hPTH (1-34) in different formulations as a function of storagetime at three different temperatures. Table 8-3 below illustrates themonomer content as determined by sec-HPLC of the hPTH (1-34) indifferent formulations as a function of storage time at three differenttemperatures. It appears that hPTH (1-34) is stable during storage forup to one month at even elevated temperature in all the formulationsexamined. (Formulation F3 was not sampled at the 1 week time point atroom temperature or 40° C.)

TABLE 8-2 F1 F2 F3 F4  5° C. t = 0 100.0 100.0 100.0 100.0 t = 1 week99.77 99.87 99.78 100.00 t = 2 week 99.76 99.71 99.65 99.74 t = 1 month99.78 99.69 99.66 99.73 t = 13 months 98.87 100.0 100.0 100.0 25° C. t =0 100.0 100.0 100.0 100.0 t = 1 week 99.75 100.0 100.0 t = 2 week 99.7299.63 99.49 99.70 t = 1 month 99.72 99.59 99.52 99.67 t = 3 months 99.7699.72 99.09 99.88 t = 13 months 100.0 98.62 99.11 98.58 40° C. t = 0100.0 100.0 100.00 100.00 t = 1 week 99.72 99.79 99.88 t = 1 month 99.5699.14 98.64 99.39

TABLE 8-3 F1 F2 F3 F4  5° C. t = 0 100.00 100.00 100.00 100.00 t = 1week 99.77 99.87 99.78 100.00 t = 2 week 99.76 99.71 99.65 99.74 t = 1month 99.78 99.69 99.66 99.73 25° C. (room temp.) t = 0 100.00 100.00100.00 100.00 t = 1 week 99.75 100.00 100.00 t = 2 week 99.72 99.6399.49 99.70 t = 1 month 99.72 99.59 99.52 99.67 t = 3 months 99.70 99.6799.52 99.77 40° C. t = 0 100.00 100.00 100.00 100.00 t = 1 week 99.7299.79 99.88 t = 1 month 99.56 99.14 98.64 99.39

Example 9 Preparation of a 2-Layer Microprojection Array ContainingHuman Parathyroid Hormone (Hpth (1-34))

A microprojection array containing a therapeutically effective amount ofhPTH (1-34) (32 μg) was prepared for use in a Phase I clinical study asfollows.

First, in describing generally the features of the microprojectionarray, the microprotrusions of the array can be characterized generallyas comprising a DIT (drug-in-tip) layer and a “backing” layer. The DITlayer includes hPTH (1-34) in a water-soluble matrix. The sequence ofhPTH (1-34) used was:

(SEQ ID NO: 1) H-Ser-Val-Ser-Glu-Ile-Gln-Leu-Met-His-Asn-Leu-Gly-Lys-His-Leu-Asn-Ser-Met-Glu-Arg-Val-Glu-Trp-Leu-Arg-Lys-Lys-Leu-Gln-Asp-Val-His-Asn-Phe-OH

The tip of the microprojections is also referred to herein as the layerat the bottom-most portion of the tips or microprotrusions (i.e.,proximal to the skin when placed upon the skin), also referred to hereinas the “end portion” that is distal to the base of the array). The“backing” layer as referred to in certain of these examples, encompassesboth the upper portion of the microprotrusions proximal to the base ofthe array as well as the base itself, where the base is the portion ofthe array that supports the tips. The backing layer comprises abiocompatible, non-water soluble matrix. In the instant array device,the material in the upper portion of the microprotrusions is the same asthe base material itself, so that the non-water soluble matrixformulation is applied as a single layer to fill the mold atop the DITlayer.

The DIT layer of the microstructure array dissolves into the skin andcontains the components provided in Table 9-1. Acetate was thecounter-ion in the hPTH (1-34) drug substance.

TABLE 9-1 Composition of Drug-in-Tip Layer of hPTH(1-34) TDS % w/w (ofthe Trade Chemical Name of Quantity Range microstructure Name Ingredient(μg/unit) (ug/unit) array) hPTH human Parathyroid 32.0 25.6-38.4 12.8(1-34) hormone (1-34) Dextran Dextran, 70,000 160.0 128.0-192.0 58.6 70Dalton molecular weight Sorbitol, Sorbitol 54.9 64.0-96.0 21.9 N.F.Histidine L-histidine 0.14 0.11-0.17 0.1 Histidine L-histidine 0.730.58-0.88 0.3 HCl hydrochloride NA Acetate 2.5 2.0-3.0 1.0 Total 250.27100.0

The backing portion or layer of the array was composed ofpoly(DL-lactide-co-glycolide), 75:25, ester terminated (Tradename:LACTEL®).

The ingredients forming the tip portion of the formulation (i.e., theDIT formulation) were dissolved in water, cast, and dried in a siliconemold containing microstructure cavities to form the drug-in-tips (DIT)structures. The water insoluble, biocompatible polymer,poly(DL-lactide-co-glycolide), 75:25, was dissolved in acetonitrile toprovide the backing formulation which was then coated on top of the DITlayer in the silicone mold, and then dried. The solvent was removed fromthe backing (upper portion proximal to the base, and base) duringprocessing and was limited to a level below the amounts recommended inICH residual solvent guidelines.

Example 10 Preparation of a Delivery Device Containing a MicroprojectionArray Containing Human Parathyroid Hormone (Hpth (1-34))

A delivery system, also referred to as an applicator-array assembly,comprising a microprojection array prepared in accord with Example 9 andan applicator as described with reference to FIGS. 1-2 , was assembledas follows. A microprojection holding member with a microprojectionarray (Example 9) was prepared and packaged, and separately anapplicator assembly (i.e., an applicator as in FIGS. 1-2 absent themicroprojection-holding member) was packaged. The two separate packageswere provided in a single boxed unit to each clinical site, for assemblyof the applicator-array assembly prior to use on a patient (see Example11 below for clinical data).

The microprojection array contained was 11 millimeters in diameter withapproximately 2700 microprojections arranged in a hexagonal pattern. Themicroprojection array was mounted on the microprojection-holding member(element 184 of FIG. 2 ) using an adhesive laminate. Themicroprojection-holding member/microprojection array was packaged insidea protective container and pouched in a dry nitrogen environment.

The applicator assembly comprised of an outer housing (element 182 ofFIG. 2 ) with a skin contact adhesive and a release liner (elements 192,194, respectively, of FIG. 2 ), an energy storage member (in this case,a metal wave spring), and elements to hold these items together. Thisapplicatory assembly was packaged inside a protective container andpouched.

Prior to use of the system, the microprojection-holdingmember/microprojection array was inserted into the applicator assembly,and the system was activated by compressing the spring and then twistingthe microprojection-holding member to lock and hold the compressedspring in place in the applicator. To initiate delivery of the hPTHdose, the user twists the microprojection-holding member to unlock orunseat it from the outer cover, thus causing the spring to release itsstored energy causing accelerated movement of themicroprojection-holding member and attached microprojection array intocontact with the skin. Upon contact with the skin, the microstructurespenetrate past the stratum corneum, and the hPTH dissolves into the skinrapidly. Following actuation of the spring and delivery of hPTH, thesystem is removed and discarded.

Example 11 In-Vivo Study: Administration of Human Parathyroid Hormone,Hpth (1-34), Via a Microprojection Array Device in Healthy HumanSubjects

An open label, single dose, sequence randomized, 3-way cross-over studywas carried out in sixteen healthy female volunteers to determine thepharmacokinetics (along with additional secondary endpoints) of 32 μghPTH (1-34) and 64 μg hPTH (1-34) (32 μg hPTH (1-34)×2) delivered usingthe TDS (“MicroCor®”) described in Examples 9 and 10 relative tosubcutaneously administered (SC) FORTEO® (teriparatide), 20 μg. Thesystem described in Examples 9 and 10 is referred to in this examplegenerally as “MicroCor® hPTH (1-34)” or for simplicity herein,“MicroCor®”.

Subjects received a single dose of 32 μg hPTH (1-34) or 64 μg hPTH(1-34) (32 μg×2) by applying the MicroCor® device to an abdominal sitefor 5 minutes. Treatment with the commercial hPTH product known asForteo® was accomplished by administration as a subcutaneous injectioninto the abdominal wall. Treatments were separated by a 48-hour washoutperiod. The plasma sampling schedule was as follows: pre-treatment, 5,10, 15, 20, 25, 30, 40, 50, 60, 75, 90, 120, 180, 240, 300, 360 minutes,and 24 hours post-treatment. Vital signs were monitored pre-treatment,and at 15 and 30 minutes, and 1, 2, 3, 4, 5, 6, 8, 10, 12, and 24 hourspost-treatment. Adverse advents were monitored throughout the study.Additional assessments included (i) measurement of anti-PTH antibodiesprior to first treatment and 2 weeks following last treatment, (ii)measurement of serum calcium, phosphorous, albumin, and protein atpre-treatment, and 1, 2, 3, 4, 5, 6, and 24 hours post-treatment, aswell as (iii) adhesion of the MicroCor® system.

Administration of hPTH transdermally via the microarray (MicroCor®treatments) demonstrated good skin tolerability. Skin effects weretransient and well-tolerated, with mild to moderate erythema observed.In terms of general safety, all treatment regimes were well-tolerated.No significant adverse events nor unexpected adverse events occurred. Infact, there was no difference in the overall treatment-related adverseevents between the MicroCor® and the Forteo®-based treatments. Nosignificant changes were observed in serum calcium, and no anti-PTHantibodies were detected, again further demonstrating the overall safetyof MicroCor®-based treatment in human subjects. Data is presented inFIGS. 3-8 and Table 1, above.

It is claimed:
 1. A microprotrusion array for transdermal administrationof a dose of parathyroid hormone (PTH) to a mammalian subject, saidarray comprising a plurality of microprotrusions extending from anapproximately planar base, each microprotrusion comprising an endportion distal to the base and an upper portion proximal to the base,wherein at least the end portion comprising the PTH in a water-solublepolymer matrix, the water-soluble polymer matrix comprising: (i) about7.5-12.8% dry weight PTH; (ii) about 20-70% dry weight of at least onedextran polymer; and (iii) about 10-35% dry weight of at least one sugaror sugar alcohol; and wherein the upper portion comprising at least onewater-insoluble polymer.
 2. The microprotrusion array of claim 1,wherein the PTH is human parathyroid hormone (1-34).
 3. Themicroprotrusion array of claim 1, wherein the at least one dextranpolymer is selected from Dextran 1, Dextran 10, Dextran 20, Dextran 40,Dextran 70 and Dextran
 75. 4. The microprotrusion array of claim 1,wherein the water-soluble polymer matrix comprises about 35-70% dryweight of the at least one dextran polymer.
 5. The microprotrusion arrayof claim 1, wherein the at least one sugar or sugar alcohol is selectedfrom sucrose and sorbitol.
 6. The microprotrusion array of claim 1,wherein the base is comprised of a water-insoluble polymer.
 7. Themicroprotrusion array of claim 1, wherein the water-insoluble polymercomprises a poly(lactic acid-co-glycolic acid).
 8. The microprotrusionarray of claim 1, wherein the array comprises a total dose of about10-100 μg PTH.
 9. The microprotrusion array of claim 1, wherein thearray comprises a total dose of about 32 μg PTH.
 10. The microprotrusionarray of claim 1, wherein the array comprises a total dose of about 64μg PTH.
 11. The microprotrusion array of claim 1, wherein at least aportion of the end portions including the tip of the plurality ofmicroprotrusions are configured to detach from the microprotrusion arrayafter the microprotrusions are inserted into the skin of the mammaliansubject.
 12. The microprotrusion array of claim 1, wherein the pluralityof microprotrusions are configured to: (a) penetrate the skin of themammalian subject when the microarray is applied to a skin site of themammalian subject, (b) administer transdermally the dose of PTH to themammalian subject when the microarray is applied to the skin site forabout 15 minutes or less, and (c) achieve an average time to maximum PTHplasma concentration (T_(max)) of about ten minutes or less.
 13. A kit,comprising: a microprotrusion array comprised of a plurality ofmicroprotrusions extending from an approximately planar base, eachmicroprotrusion comprising an end portion distal to the base and anupper portion proximal to the base, the end portion of eachmicroprotrusion comprising parathyroid hormone (PTH) in a water-solublepolymer matrix comprising about 7.5-12.8% dry weight PTH, about 20-70%dry weight of at least one dextran polymer, and about 10-35% dry weightof at least one sugar or sugar alcohol, and the upper portion beingcomprised of at least one water-insoluble polymer, said array comprisinga therapeutically effective amount of PTH in the water-soluble polymermatrix, and an applicator-assembly to which the microprotrusion array isinsertable or affixable; wherein at least the end portion of eachmicroprotrusion is fabricated to achieve an average time to maximum PTHplasma concentration (T_(max)) of about ten minutes or less when appliedto a subject.
 14. A method of transdermally administering a dose of PTHto a mammalian subject, comprising: (a) applying to a skin site of asubject a microprotrusion array comprising a plurality ofmicroprotrusions extending from an approximately planar base, eachmicroprotrusion comprising an end portion distal to the base and anupper portion proximal to the base, the end portion comprising a tip ofthe microprotrusion, at least the end portion comprising parathyroidhormone (PTH) in a water-soluble polymer matrix, (b) inserting all or aportion of the plurality of microprotrusions into the skin, and (c)maintaining the array on the skin site for about 15 minutes or less;whereby the method achieves an average time to maximum PTH plasmaconcentration (T_(max)) of about ten minutes or less.